The M37 was the last of the .30 caliber air-cooled Brownings adopted by the US military.

After WW2 the Army needed an improved tank machine gun. The 1919A4 had some drawbacks as a coaxial tank MG, so work began around 1950 to produce a serviceable weapon.

The M37 can be fed from either side and has a link chute opposite the feed side. The bolt has dual tracks for alternate operation of the belt feeding pawl. The pawl can be reversed and the pawl lever moved to the other side. Two wedge shaped switches close off the unused track, and the ejector can be reversed. The top cover can easily be opened from either side by rotating a winged knob. The gun is charged from the rear via a retracting slide. The driving spring is captive and is secured to the right side plate at the rear by sliding a conical block into a dovetailed slot. There is no driving spring rod protruding through the back plate. The back plate envelopes the receiver sides and can be easily removed by depressing a latch at the top. There is a horizontal trigger safety, and the left side sight base has been eliminated. The rear sight base is integral to the top plate.

The M37 was primarily a tank gun and was used on both the M48 & M60 Patton medium tanks. The fixed version, the M37C was also used on the OH-13 Sioux and OH-23 Raven helicopter gunships on the skid-mounted M1 armament sub-system.

For the most part the M37 is a highly modified (and improved) Browning 1919 which can feed from the right or left.